Various smart material actuator technologies have been developed for a wide range of applications in different industries. One component used in this type of actuator is an electrically stimulated smart material actuator. These smart material actuators when electrically stimulated change shape. This shape change can be designed such that one axis predominantly changes. Such a smart material actuator can be incorporated within a main support structure. As the axis of the smart material actuator changes dimension its motion is magnified by a lever integral to the main support structure. As a result of the magnification factor developed by the main support structure, extremely small differences of thermal coefficients of expansion between the smart material and main support structure can create relatively large movements of output in the main support structure over normal operating temperature ranges. This movement can be as much as fifty percent of the usable output of the actuator system.
Previous designs place the compensating element in line with the smart material. This method suffers from several problems. One such problem is the length of the compensating element inserted between the main body and the smart material increases the overall length of the actuator. Further smart materials are capable of delivering large amounts of force, so the compensating element must be sufficiently stiff to prevent a reduction of the force and movement performance of the actuator while acting as the inline compensating element. This is a difficult combination to achieve with inexpensive materials.
Another common design is to place sleeves with different coefficients of thermal expansion around the smart material causing the cavity that captures the smart material to expand and contract with temperature. This system uses several parts, all of which are complex, and costly to machine and increases the overall size making it less desirable.